🛠️ Functions in Rust
Why Functions?
Functions are the building blocks of every Rust program. They help you write reusable, organized, and expressive code.
📌 Defining a Function
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- Function names use snake_case by convention
- Call a function with its name and parentheses
📥 Parameters
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📌 Each parameter must have a name and a type. Rust is strict about types—no guessing here!
🎁 Return Values
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✅ The last expression in a function is the return value—no return
needed unless you want to return early.
If you do use return
, add a semicolon:
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❌ But if you end with an expression, do not use a semicolon:
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⚙️ Statements vs Expressions
- Statements do something but return nothing (e.g.,
let x = 5;
). - Expressions evaluate to a value (e.g.,
5 + 2
,x * y
, blocks like).
Since Rust is expression-oriented, you can use blocks to return values:
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💡 Why Functions Matter
- Make your code easier to read and maintain
- Help you organize logic into small, testable chunks
- Allow you to reuse behavior across your app
Rust also supports advanced patterns like:
- Function pointers
- Closures (anonymous functions)
- Higher-order functions
…but we’ll get there later 😎
🧠 Summary
- Define functions with
fn
- Use parentheses
()
for parameters - Return values with
->
and no semicolon on the last line - Embrace expressions—Rust loves them!
Mastering functions early will unlock a lot of power in your Rust journey 🦀